An electronic piano generally detects existence/absence of a key operation, a key depression speed, and a key release speed by a key switch provided in each key. The electronic piano controls a volume and a tone in correspondence with the detected key depression speed and key release speed. By such control, it becomes possible to change the volume and the tone corresponding to key touch.
Further, as a key switch, two key switches constituted to turn on sequentially by two key strokes of short and long strokes are generally used. When such two key switches are used, a time difference between two key switches turning on is counted by a counter and a key speed is detected (see Patent Literature 1).